Retarding mechanisms for rotary devices are needed in many installations. By way of specific example, draft beer is often supplied in stainless steel kegs which are rather expensive and which must be reused many times in order to be cost effective. It is common practice to unload such kegs of beer from a truck by placing a rubber pad on the pavement, which may be concrete, and then dropping the kegs onto the pad. Notwithstanding the pad a keg may land on an edge where area forces may be quite high, resulting in denting or other damage to the keg. Furthermore, the driver or other delivery men may be rushed and may occasionally miss the pad with a keg, resulting in severe damage to the keg. Damage may also be incurred if the keg bounces off the pad onto the concrete.
A keg can be lowered from the back of a truck by a sling on a cable passed over a pulley arrangement. However, it is undesirable to have the cable and pulley arrangement operated manually as this slows operations and increases labor costs. If some sort of speed retarder mechanism could be utilized in such a system time delay would be minimized and labor costs would not be increased.
Retarders also can find use in conveyor pulleys to control the speed of a belt conveying material down a slope, or they can be used as speed limiters or governors.